(a) Field of the Invention
The present invention relates to a digital recording system (DRS). More specifically, the present invention relates to a digital image data compression device of a digital recording system.
(b) Description of the Related Art
A digital recording system stores and transmits image information in a digital format in replacement of an analog recording system. The digital recording system is applied to various fields using image transmission techniques such as video conferencing, unmanned store management systems and traffic control systems.
In order to effectively store a huge amount of digital image data, the digital recording system compresses, stores and transmits the image data and decompresses the transmitted data into original image data and outputs the same.
Techniques for compressing the digital image data include MPEG, MJPEG, JPEG, Wavelet and Fractal systems.
The MPEG and MJPEG systems for compressing moving pictures compare pixels of the image data of a previous image with those of a present image to compress the same, and accordingly, much compression time and huge storage capacity are needed.
Also, since the image information can be lost when decompressing the compressed image data, blocks of decompressed image data are generated, and therefore the image quality becomes deteriorated, and users should pay a lot of money to use the compression methods.
The Wavelet or Fractal techniques for compressing still images per frame reduce data processing time when compressing or decompressing the data, and since the blocks are not generated, the decompressed image is clear.
However, since they only compress still images and they cannot compress moving pictures, and since there is no international standard, compatibility problems occur.
Also, in the case the digital recording system is provided to an unmanned shop or unmanned bank, the digital recording system continues to operate and compresses and stores image data even when no particular events occur in the night because of few users.
Accordingly, because of the repeated compression process, the storage capacity of the storage device is unnecessarily spent, and because of the unnecessary storing process of identical images, the lifespan of the storage device is shortened.